Target viewing devices such as gun/weapon sights, spotter scopes, telescopes, microscopes, monoculars, binoculars and the like are example forms of direct view optical devices. In devices such as gun/weapon sights, reticles are projected onto LCD screens incorporated into the gun/weapon sight. The LCD screens are typically full color display devices, and in most cases the projected reticle is monochromatic. So only a small portion of the capabilities of the LCD screens are used. In addition, LCD screens are expensive, generate a significant amount of heat, and consume a significant amount of power.
Moreover, LCD screens used in gun/weapon sights generally cover the entire field of view or project onto screens that cover the entire viewing area. A screen that obscures the entire field of view reduces the light transmission across the entire field of view. In low light vision applications, small reductions in visible light transmission significantly reduce the ability to identify targets through the sight.